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/*$Source: /usr/home/dhesi/booz/RCS/huf.c,v $*/
/*$Id: huf.c,v 1.8 91/07/08 12:06:53 dhesi Exp $*/
/***********************************************************
Static Huffman
Adapted from "ar" archiver written by Haruhiko Okumura.
***********************************************************/
#include "booz.h"
#include "zoo.h"
#include "ar.h"
#include "lzh.h"
#define NP (DICBIT + 1)
#define NT (CODE_BIT + 3)
#define PBIT 4 /* smallest integer such that (1U << PBIT) > NP */
#define TBIT 5 /* smallest integer such that (1U << TBIT) > NT */
#if NT > NP
# define NPT NT
#else
# define NPT NP
#endif
int decoded; /* for use in decode.c */
ushort left[2 * NC - 1], right[2 * NC - 1];
static uchar c_len[NC], pt_len[NPT];
static uint blocksize;
static ushort c_table[4096], pt_table[256];
static int read_pt_len(nn, nbit, i_special)
int nn;
int nbit;
int i_special;
{
int i, c, n;
uint mask;
n = getbits(nbit);
if (n == 0) {
c = getbits(nbit);
for (i = 0; i < nn; i++) pt_len[i] = 0;
for (i = 0; i < 256; i++) pt_table[i] = c;
} else {
i = 0;
while (i < n) {
c = bitbuf >> (BITBUFSIZ - 3);
if (c == 7) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 3);
while (mask & bitbuf) { mask >>= 1; c++; }
}
fillbuf((c < 7) ? 3 : c - 3);
pt_len[i++] = c;
if (i == i_special) {
c = getbits(2);
while (--c >= 0) pt_len[i++] = 0;
}
}
while (i < nn) pt_len[i++] = 0;
make_table(nn, pt_len, 8, pt_table);
}
}
static int read_c_len()
{
int i, c, n;
uint mask;
n = getbits(CBIT);
if (n == 0) {
c = getbits(CBIT);
for (i = 0; i < NC; i++) c_len[i] = 0;
for (i = 0; i < 4096; i++) c_table[i] = c;
} else {
i = 0;
while (i < n) {
c = pt_table[bitbuf >> (BITBUFSIZ - 8)];
if (c >= NT) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
do {
if (bitbuf & mask) c = right[c];
else c = left [c];
mask >>= 1;
} while (c >= NT);
}
fillbuf((int) pt_len[c]);
if (c <= 2) {
if (c == 0) c = 1;
else if (c == 1) c = getbits(4) + 3;
else c = getbits(CBIT) + 20;
while (--c >= 0) c_len[i++] = 0;
} else c_len[i++] = c - 2;
}
while (i < NC) c_len[i++] = 0;
make_table(NC, c_len, 12, c_table);
}
}
uint decode_c()
{
uint j, mask;
if (blocksize == 0) {
blocksize = getbits(16);
if (blocksize == 0) {
decoded = 1;
return 0;
}
read_pt_len(NT, TBIT, 3);
read_c_len();
read_pt_len(NP, PBIT, -1);
}
blocksize--;
j = c_table[bitbuf >> (BITBUFSIZ - 12)];
if (j >= NC) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 12);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NC);
}
fillbuf((int) c_len[j]);
return j;
}
uint decode_p()
{
uint j, mask;
j = pt_table[bitbuf >> (BITBUFSIZ - 8)];
if (j >= NP) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NP);
}
fillbuf((int) pt_len[j]);
if (j != 0) j = ((unsigned) 1 << (j - 1)) + getbits((int) (j - 1));
return j;
}
int huf_decode_start()
{
init_getbits(); blocksize = 0;
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.